Electrosurgery is a widely accepted technique and is used to perform a variety of manual or robot-assisted surgical procedures on biological tissue. For example, electrosurgery is used to hemostatically occlude blood vessels, as well as to perform tonsillectomies, vaginal hysterectomies, and amputation of the liver tip and splenic wedge, as well as to treat polycystic ovary syndrome, remove benign and malignant lesions of the skin, and to perform intradiscal electrothermal therapy for internal disc disruptions of the spine. However, surgeons that utilize currently available robotic and manual laparoscopic electrostimulation devices for electrosurgery are often unable to prevent collateral damage, such as the overheating, charring, and tearing of the tissue surrounding the surgical site. Collateral damage is caused by the uncontrolled spread of energy from the electrostimulation device through tissue that is located in and about the surgical site. Furthermore, the rate of collateral damage caused by laparoscopic electrosurgical stimulators due to the uncontrolled spread of electricity also tends to increase with repeated use of such electrosurgical devices. Unfortunately, such collateral damage often leads to surgical complications, increased pain and discomfort, and longer hospital stays, which increase the costs to the patient.
Although current commercially-available electrosurgical devices use a constant stimulation frequency that is between about 300 kHz to 3 MHz, for example, the biological tissue being treated by such devices has a conductivity that is dependent on the stimulation frequency used. For example, biological tissue, including kidney, liver, lung, heart, spleen, uterus, thyroid, testes, ovary, bladder, tongue, cartilage, muscle, and skin tissue all have an electrical conductivity that tends to increase with increasing stimulation frequencies. However, there are many other examples showing that the conductivity of these tissues can increase by more than two orders of magnitude over a frequency range from 10 Hz to 20 GHz. In addition, changes in electrical conductivity in biological tissue may also be caused by mechanical changes in the structure of biological tissue itself. For example, it has been shown that the electrical conductivity of porcine lung tissue has a large variation in depending on whether the lung is inflated or deflated, which is due to the significant mechanical changes of the structure of the lung during pneumoconstriction. Thus, a wide array of electrosurgical procedures can be positively impacted by providing a variable-frequency stimulator device that is able to deliver an adjustable stimulation frequency to increase the conductivity of the tissue being treated.
In addition, while electrosurgical techniques have improved due to various technological breakthroughs, including advancements in controlling the electrical current, clinically-relevant problems still exist with robotic and manual laparoscopic electrosurgical devices. Thus, surgeons still have difficulty avoiding collateral damage in and about the surgical site being treated by electrosurgical devices. As such, surgical complications from electrosurgery still frequently occur, which result in patient dissatisfaction and increased hospitalization costs, which are unwanted.
Therefore, there is a need for a variable-frequency stimulator for electrosurgery, which controls the conductivity of the biological tissue by varying a stimulation frequency. In addition, there is a need for a variable-frequency stimulator for electrosurgery that can be readily used with any commercially available robotic or manual electrosurgical device, such as a tissue dissector or laparoscope. There is also a need for a variable-frequency stimulator that provides improved electrosurgical efficacy and safety margins, and that reduces the occurrence of collateral damage to tissue surrounding the surgical site being treated. Moreover, there is a need for a laparoscope for use with a variable-frequency stimulator that is configured to concentrate the electrical current near the surface of the surgical site to prevent the uncontrolled spread of electrical current through the tissue, so as to reduce or prevent collateral damage to nearby tissue.